To modify a curve, you select and manipulate its nodes. Here are some of the things you can do with nodes :
Of course, in order to work with nodes, you must first select them.
Select a curve object (or one that has been converted to a curve object) with the Shape Tool. The object's nodes appear on the shape's path. (Check the status bar to make sure that the object is a curve.)
Click a node with the Shape Tool to select it (Figure 6.9).
Figure 6.9. Use the Shape Tool ...